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Wed, 24 Sep 2025 04:52:10 -0700 (PDT) From: Jinchao Wang To: Andrew Morton , Masami Hiramatsu , Peter Zijlstra , Mike Rapoport , Alexander Potapenko , Randy Dunlap , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. 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Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v5 10/23] mm/ksw: support CPU hotplug Date: Wed, 24 Sep 2025 19:50:53 +0800 Message-ID: <20250924115124.194940-11-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250924115124.194940-1-wangjinchao600@gmail.com> References: <20250924115124.194940-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: B858EC000E X-Stat-Signature: oai11yupunrkzrfp1c36zkzmot3dof7o X-Rspam-User: X-HE-Tag: 1758714732-766957 X-HE-Meta: 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 j6BYrVNg 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Register CPU online/offline callbacks via cpuhp_setup_state_nocalls() so stack watches are installed/removed dynamically as CPUs come online or go offline. When a new CPU comes online, register a hardware breakpoint for the holder, avoiding races with watch_on()/watch_off() that may run on another CPU. The watch address will be updated the next time watch_on() is called. Signed-off-by: Jinchao Wang --- mm/kstackwatch/watch.c | 52 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) diff --git a/mm/kstackwatch/watch.c b/mm/kstackwatch/watch.c index 722ffd9fda7c..f32b1e46168c 100644 --- a/mm/kstackwatch/watch.c +++ b/mm/kstackwatch/watch.c @@ -89,6 +89,48 @@ static void ksw_watch_on_local_cpu(void *info) WARN(ret, "fail to reinstall HWBP on CPU%d ret %d", cpu, ret); } +static int ksw_watch_cpu_online(unsigned int cpu) +{ + struct perf_event_attr attr; + struct ksw_watchpoint *wp; + call_single_data_t *csd; + struct perf_event *bp; + + mutex_lock(&all_wp_mutex); + list_for_each_entry(wp, &all_wp_list, list) { + attr = wp->attr; + attr.bp_addr = (u64)&holder; + bp = perf_event_create_kernel_counter(&attr, cpu, NULL, + ksw_watch_handler, wp); + if (IS_ERR(bp)) { + pr_warn("%s failed to create watch on CPU %d: %ld\n", + __func__, cpu, PTR_ERR(bp)); + continue; + } + + per_cpu(*wp->event, cpu) = bp; + csd = per_cpu_ptr(wp->csd, cpu); + INIT_CSD(csd, ksw_watch_on_local_cpu, wp); + } + mutex_unlock(&all_wp_mutex); + return 0; +} + +static int ksw_watch_cpu_offline(unsigned int cpu) +{ + struct ksw_watchpoint *wp; + struct perf_event *bp; + + mutex_lock(&all_wp_mutex); + list_for_each_entry(wp, &all_wp_list, list) { + bp = per_cpu(*wp->event, cpu); + if (bp) + unregister_hw_breakpoint(bp); + } + mutex_unlock(&all_wp_mutex); + return 0; +} + static void ksw_watch_update(struct ksw_watchpoint *wp, ulong addr, u16 len) { call_single_data_t *csd; @@ -210,6 +252,16 @@ int ksw_watch_init(void) if (ret <= 0) return -EBUSY; + ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "kstackwatch:online", + ksw_watch_cpu_online, + ksw_watch_cpu_offline); + if (ret < 0) { + ksw_watch_free(); + pr_err("Failed to register CPU hotplug notifier\n"); + return ret; + } + return 0; } -- 2.43.0